1. Field of the Invention
The present invention pertains to an apparatus for managing heat in a computer environment or the like. More particularly, the present invention pertains to a method and apparatus for managing heat generated by electronic circuitry using a base plate and/or input/output plate with an integrated heat pipe.
2. Background Information
Electronic circuits, particularly integrated circuit (IC) chips, tend to generate an appreciable amount of heat during operation. If the heat is not sufficiently removed from the ambient area surrounding the IC chip, the electronic circuit therein may not operate properly. For example, specifications for a Pentium.RTM. processor (Intel Corporation, Santa Clara, Calif.) operating at 66 Megahertz (MHZ) provide a maximum temperature of 70.degree. C. for the ambient air surrounding the processor. Thus, if the temperature of the ambient air surrounding the processor exceeds this maximum temperature, there exists a possibility that the processor will not operate correctly.
Referring to FIG. 1, a view of a laptop computer 10 is shown. Laptop computer 10 includes a screen 11 and a main chassis 12. As is known in the art, the main chassis includes a keyboard component 13 having a support plate onto which is mounted a printed circuit board (PCB) and a plurality of keys. Under keyboard component 13 is another PCB 15 (sometimes referred to as a motherboard) which may include components such as one or more processors (e.g., a Pentium.RTM. processor), memory modules, and a variety of other electronic components. PCB 15 may be mounted to a base plate 17 extending over an area of a base 18 of laptop computer 10. Laptop computer 10 also includes an Input/Output (I/O) plate 19 which is at a back end 20 of the computer 10 in this example. The I/O plate 19 includes a number of openings that house connections that may be coupled to any of a variety of peripheral devices (e.g., an external floppy drive, a docking station, etc.).
Certain components on PCB 15 (e.g., the processor) generate more heat than others. Some known methods for dissipating heat from the Pentium.RTM. processor set forth above are described in Application Note APA480 "Pentium.RTM. Processor Thermal Design Guidelines Rev. 2.0," Nov. 1995 (see, e.g., Pentium.RTM. and Pentium.RTM. Pro Processors and Related Products, 1996, pp. 2-1337 to 2-1363 obtainable from McGraw-Hill Book Company). These methods include the placement of a heat sink on top of the processor and increasing air flow over the processor so that the ambient air (heated by the processor) may be removed. In a personal computer environment, the processor is typically coupled electrically to other devices on a PCB. These other devices also generate heat and employ the above identified heat removing methods to operate correctly.
Another device for removing heat from a component, such as a processor, is a heat pipe. A heat pipe typically has a round cross-section including two paths extending the length of the pipe. The heat pipe (e.g., an end of the heat pipe) is placed proximately to a component, such as a processor. Working fluid in the heat pipe (e.g., water) is heated at the component and vaporized. The vapor travels away from the component in a hollow, first path of the heat pipe (this first path typically has a relatively large cross-sectional area). Eventually, the vapor is cooled at another location in the heat pipe. For example, the vapor may be cooled over a heat sink device mentioned above. The vapor condenses to form working fluid and the working fluid travels back to the processor through a second path, sometimes referred to as a wick structure, via capillary action. Thus, the heat pipe continuously circulates working fluid and vapor to remove heat from the processor. Further details on the operation of heat pipes can be found in Handbook of Applied Thermal Design (1989, ed., Eric C. Guyer, pp. 7-50 to 7-58).
The use of devices for managing heat becomes very important in mobile computer systems, such as laptop computer 10 shown in FIG. 1. Because of their small size, especially in height, there is generally insufficient space for air flow past components in a laptop computer. Base plate 17 is made of a metal such as steel or aluminum which tends to conduct the heat generated by components on PCB 15 to all areas of base plate 17. Also, base plate 17 and I/O plate 19 may be combined into a single L-shaped plate 25 shown in FIG. 2. Doing so expands the area for spreading the heat generated by PCB components. Due to the relatively poor thermal conductivity of these metals, thermal gradients do occur in the base plate, which in turn causes some sections of base plate 17 and/or I/O plate 19 to be warmer than others thus limiting the thermal capabilities.
Heat pipes, as described above, may be used to improve heat management in laptop computers having a base plate 17 and I/O plate 19. The heat pipe is typically used to couple the heat of the processor to the base plate 17. Doing so has at least two significant drawbacks. First, incorporating heat pipes into the computer structure increases manufacturing costs and complexity in that it is desirable for the heat-pipe to be precisely placed and attached to the PCB adding a number of manufacturing steps to laptop computer fabrication. Also, the heat pipe is attached to the PCB in different locations creating a situation where some areas on the PCB are hotter than others. These differences in temperature may be perceived by a user, and the efficiency of the heat removal system is reduced. Accordingly, there is a need for an apparatus for improving heat management for electronic circuits, especially for laptop and notebook computers.